1. Field of the Invention
This invention relates to a burner for waste gases such as those which are generated by decomposition on landfill sites at which refuse is deposited. Such waste gases consist principally of inflammable methane gas but which may also contain other gases having a higher or lower degree of flammability, vapours and dust, any of which may be composed of or contaminated with biologically dangerous chemicals. It is necessary to dispose of the waste gas efficiently since otherwise there is a risk of explosion or uncontrolled burning and it is also necessary to ensure that any harmful contaminants are rendered harmless so as to avoid environmental pollution and health hazards.
2. Description of the Prior Art
The techniques previously used for burning waste gas have been derived from the technology developed in the incineration of domestic waste. Municipal and similar large-scale domestic waste incinerators use high chimneys and rely on the production of a high temperature, between 1100.degree. C. and 1200.degree. C., for a long residence time, typically of the order of two seconds. It has been found that this relatively long period of burning at the appropriate temperature is needed to ensure that complete incineration of the refuse occurs without the formation of environmentally harmful oxides of nitrogen in substantial quantities.
However, the burning of waste gas is not completely analogous to the burning of domestic refuse and it is therefore to be supposed that the same criteria will not apply. Nevertheless, it is customary for waste gas burners to use relatively long retention times and temperatures in the same region, 1200.degree. C., as in refuse incinerators.